Impulse transmitter for dynamic devices for testing pieces of ordnance

ABSTRACT

An impulse transmitter for dynamic devices for testing pieces of ordnance to simulate the recoil of the piece without actual firing. The impulse transmitter includes a housing having a cylinder receiving a propellent charge and the rear portion of a piston, the forward portion of the piston extending from the housing for abutment against the barrel of the piece of ordnance. The cylinder is provided with apertures which open into a chamber formed in the housing which has a volume greater than the volume of the cylinder through which the piston moves during the working stroke. The chamber is provided with a venting valve for venting the chamber to the atmosphere such that when the propellent charge is ignited, the gases formed thereby cause forward movement of the piston against the barrel with the firing report being intensively damped such that the gases flow from the cylinder into the atmosphere with only a hissing sound.

Apr. 17, 1973 IMPULSE TRANSMITTER FOR DYNAMIC DEVICES FOR TESTING PIECES OF ORDNANCE Dieter Boder, Dusseldorf-Oberkassel, Germany Rheinmetall GmbH, Dusseldorf, Germany Filed: Nov. 3, 1971 Appl. No.: 195,302

Inventor:

Assignee:

Foreign Application Priority Data Dec. 5, 1970 Germany ..P 20 59 956.8

US. Cl ..73/l67, 73/11, 73/432 SD Int. Cl. ..G0lm 7/00, F4lf 25/00 Field of Search ..73/l67, 432 SD, 11

References Cited UNITED STATES PATENTS Bourgeot ..73/167 Primary Examiner-Louis R. Prince Assistant Examiner-Joseph W. Roskos Att0rneyCraig, Antonelli & Hill ABSTRACT An impulse transmitter for dynamic devices for testing pieces of ordnance to simulate the recoil of the piece without actual firing. The impulse transmitter includes a housing having a cylinder receiving a propellent charge and the rear portion of a piston, the forward portion of the piston extending from the housing for abutment against the barrel of the piece of ordnance. The cylinder is provided with apertures which open into a chamber formed in the housing which has a volume greater than the volume of the cylinder through which the piston moves during the working stroke. The chamber is provided with a venting valve for venting the chamber to the atmosphere such that when the propellent charge is ignited, the gases formed thereby cause forward movement of the piston against the barrel with the firing report being intensively damped such that the gases flow from the cylinder into the atmosphere with only a hissing sound.

22 Claims, 5 Drawing Figures PAITENTEUAPRIYIQHI SHEEI10F3 IMPULSE TRANSMITTER FOR DYNAMIC DEVICES FOR TESTING PIECES OF ORDNANCE The present invention relates to an impulse transmitter for dynamic devices for testing pieces of ordnance.

In pieces of ordnance having a recoil of the barrel, the strain on the gun mounting and the operation of the recoil mechanisms mainly depend on the recoil speed which is imparted to the barrel at the time of firing. It is therefore fundamentally possible to test the stability and operation of the gun mounting including the recoil' mechanism without actually firing the ordnance piece in that a simulation firing recoil speed is imparted to the barrel by a powder-driven impulse transmitter acting on the barrel of the piece arranged on a test rig.

The impulse transmitters utilized operate on the piston/cylinder principle and provide savings in that small amounts of powder are used which are a fraction of the weight of the powder charge required for the actual shot and that the firing of a projectile is not required. In addition, there is also a saving in that the barrel of the piece of ordnance is not utilized for firing a projectile, thereby eliminating additional wear of the barrel. The known powder-operated impulse transmitters all operate according to the principle of open construction, i.e. at the end of the working stroke the powder gases are guided directly from the combustion chamber into the atmosphere in such a way that a piston connected to the barrel of the piece leaves the cylinder. Since the gas pressure, when the piston emerges, lies within the same order of magnitude as the muzzle gas pressure at the time when the piece actually fires, an explosion occurs which is similar to the explosion which occurs at the time of an actual shot. Thus, the powder-operated impulse transmitters having an open construction can only be operated on a firing range. Moreover, the mass of the recoiling parts of the piece of ordnance to be tested is inaccurate in that it includes the piston attached to the barrel of the piece. Since the mass includes the piston with the recoiling parts of the piece, which mass is braked by the buffer brake of the piece, the braking forces exerted on the gun mounting do not exactly correspond to those braking forces occurring at the time of an actual shot.

The known impulse transmitters suffer from the common disadvantage that the powder gases are conveyed from the combustion chamber directly into the atmosphere at the end of the piston stroke, after the latter has left the cylinder. The open construction of the impulse transmitter provides a gas pressure at the time the piston leaves the cylinder which corresponds approximately to the muzzle gas pressure at the time a projectile leaves the muzzle and thereby leads to a muzzle blast which is similar to that at the time a live projectile is fired. Such a muzzle blast permits the use of known impulse transmitters only on the open area of a firing range, and in addition, its range of performance is limited by the cartridge caliber associated with it.

The present invention overcomes the disadvantages of the prior art by providing an impulse transmitter for dynamic devices for testing pieces of ordnance having an intensive damping of the firing blast, so that the impulse transmitter for the testing device can even be utilized in an industrial-residential area such as in a repair shop for pieces of ordnance. In addition, the present invention provides for increasing the range of efficiency of the impulse transmitter.

According to the invention, there is provided a cylinder located in the impulse transmitter housing and receiving both'the cartridge as well as the rear end of the piston. The cylinder is provided with outlet apertures which open into a chamber when a certain piston stroke has been covered, the chamber being in communication with the atmosphere by a venting valve arrangement and having a volume which is a multiple of the volume of the piston stroke. In accordance with a feature of the invention, the chamber volume is at least ten times greater than the stroke volume of the piston, so that with the aid of the venting valve arrangement located in the impulse transmitter housing, the firing report is damped so intensively that the gases flow from the venting valve into the atmosphere with only a hissing sound. Depending on the size of the powder charge of the cartridge, it may be necessary to vary the venting valve action in accordance with the power charge. In addition, the outlet apertures are provided with deflection bodies to protect the wall of the housing from burning when the hot gases flow outwardly.

The present invention provides a hydraulic braking device which is associated with the piston and acts against the impulse transmitter housing and the cylinder. The braking device includes a brake housing attached to the cylinder and having an inner surface which becomes increasingly narrower in the direction of the piston stroke and a displacement body cooperating therewith and located on the surface of the piston. The coordination of the diameter of the braking cylinder housing which becomes increasingly narrower and of the displacement body make it possible that at the beginning of the working stroke only a small braking action occurs as a result of the large throttle cross section. However, after the recoiling parts of the piece reach a predeterminedspeed, there is provided a sudden reduction of the cross section of flow so that the full braking of the piston occurs. In accordance with a feature of the invention, the brake housing is connected by a piston bore to a compensating chamber provided inside the piston, which chamber is inturn limited by a piston which is free moving and acted upon by a gas under pressure. This arrangement serves for supplying the brake fluid to an additional compensating chamber and for accommodating expansion due to heating of the fluid during the braking action which causes expansion of the fluid. The braking device may surround the piston concentrically or in accordance with another embodiment of the present invention, one or more buffer brakes may be arranged along the parallel axis in the vicinity of the piston rod. Furthermore, there is provided a recoil spring associated with the piston and supported against the brake housing for returning the piston to its initial position.

According to another feature of the invention, thev piston is provided with two pressure plates separated by the latter and the pressure plate nearest the piston and between the latter and the piston to insure the centering of the piston within the barrel of the piece of ordnance.

In order that the impulse transmitter may be usable over a large performance range, the powder chamber is dimensioned such that cartridges of different calibers can be adapted to the size of the loading chamber by the appropriate addition of single or multipart taper sleeves. In accordance with a further feature of the present invention, the impulse transmitter is arranged for travel by means of wheels on a track of rails and is providedwith a recoil brake arranged in parallel with a recuperator. The ends of the recuperator and recoil brake located at the front in the direction of the piston stroke are attached to stationary. bearings independent of the impulse transmitter.

It is therefore an object of the present invention to provide an impulse transmitter for dynamic testing of pieces of ordnance which overcomes the disadvantages of prior art arrangements.

It is another object of the present invention to provide an impulse transmitter which may be utilized in industrial or residential areas. I

It is a further object of the present invention to provide an impulse transmitter which may be utilized over a large performance range.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings, in which:

FIG. 1 is a partial sectional view illustrating the general arrangement of an impulse transmitter located in the operating position with the barrel muzzle of a piece of ordnance;

FIG. 2 is an end view of the impulse transmitter of FIG. 1;

FIG. 3 is a sectional view taken along lines III-III of FIG. 2 and illustratingthe general arrangement of an impulse transmitter according to the present invention on a larger scale;

FIG. 4 is an enlarged sectional view of the powder chamber of the impulse transmitter and FIG. 5 is an enlarged sectional view of another embodiment of a braking device for the impulse transmitter utilizing one or more buffer brakes or recuperators.

Referring now to the drawings wherein like reference numerals designate like parts throughout the several views and more particularly to FIG. 1, there is shown the impulse transmitter of the present invention including an elongated, thickwalled housing 1 which is guided for back and forth movement with its laterally located wheels 2 in a track 3 of rails. Between the impulse transmitter housing I and the base of the track 3 of rails, there are arranged a recoil brake 4 and a recuperator 5 along parallel axis with the rear portions of each-being respectively connected to a bearing lug 4a and 5a of the impulse transmitter housing 1, and the front portions of the brake 4 and the recuperator 5 being respectively .attached to a stationary support bearing 4b and 5b located on the rails 3.

of symmetry and in the axial direction, having bores for receiving a powder chamber 8 for a cartridge 9 and a piston 10. The piston 10 is only guided in the cylindrical member 6 at its rear, solid end within the housing whereas the front end of the piston projects from the impulse transmitter housing 1 and is adapted to be inserted in the barrel R of a piece of ordnance to be tested. Starting from the cylinder bore used for guiding the piston there are provided several radial outlet apertures 11 which pass through both the cylindrical member 6 and the inner wall ofa chamber 12. This chamber is so dimensioned that it occupies the upper, lateral and rear region of the impulse transmitter housing 1. As shown, the outlet apertures 11 are preferably provided with deflector bodies 1 1a.

As shown in FIG. 3, the piston 10 is solid in the region of its face which is acted upon by the powder gases. The piston is provided with bore 10a extending as far as the front end which is closed by an upper pressure plate 13. In front of the pressure plate 13 there is located an elastic intermediate plate 14 which is enclosed at the side adjacent the muzzle of the ordnance piece by a pressure plate 16 having a centering cone 15. The plates are secured together in the axial direction by a tie-rod 17 having a spring 18 mounted thereon and are clamped to each other in the radial direction such that the centering of the piston shaft within the barrel is assured.

A brake housing 19 lies concentrically about the piston 10 and is mounted at one end in the cylindrical member 6 and at the other end terminates with the front end of the impulse transmitter housing 1. The bores of the brake housing 19 serve for guiding the piston 10 and are provided with sealing rings since the brake housing 19 is filled with'brake fluid. The part of the brake housing 19 adjacent the cylindrical member 6 is provided with an aperture of large cross section due to a thin, cylindrical inner wall. After a shoulder 19 a of the housing, there is provided a tapering portion 19b which extends to the front bore of the brake housing. The piston 10 is provided with one or more piston apertures 20 and is surrounded'by an annular displacement member 21 which, in the unaffected state of the piston 10, projects into the rear, cylindrical chamber of the brake housing 19. The bore 10a of the piston is provided with a free moving compensator piston 22 which serves as a boundary between a compensator chamber 23 filled with brake fluid in the piston bore 10a, and a chamber 24 in the piston bore 10a which is filled by gas under pressure which acts on the piston 22. The impulse transmitter also includes a recuperator spring 25 located around the rear part of the piston 10 abutting against the end face of the piston 10 and against the brake housing 19. e

The impulse transmitter housing 1 is provided with a venting valve arrangement 26, which is constructed as a labyrinth throttle. The throttle action of the valve may be varied in accordance with the requirements of the impulse transmitter. As shown in FIG. 3, the outer casing of the impulse transmitter housing 1 can be partially or entirely covered, as required, with an additional sound-absorbing insulation sheath 27.

In order to cover the maximum possible performance range with a single impulse transmitter, the present in-' vention provides that cartridges 9 of different calibers can be used. Thus, as shown in FIG. 4, if a smaller cartridge 9 is to be inserted in the powder chamber 8, then the latter is increased to the correct size of the powder chamber 8 by the provision of one or more intermediate sleeves 28. The gap between the wall of the powder chamber 8 and the intermediate sleeve 28 is sealed by appropriate annular packing seals 29 or an elastic packing 30 or by both together. In any case, the base of the cartridge having a threaded percussion primer 9a abuts against the wedge-type breechblock 7 which is provided with a mechanical or electrical ignition device 31.

The brake device may also be constructed in a different manner if there are no brake housing 19, displacement body 21 and chambers 23 and 24 located on either side of the free-moving piston 22 in the hollow piston 10. As shown, for example in FIG. 5, there are provided for this purpose around the piston 10 and extending in parallel to the piston axis, one or more hydraulic buffer brakes 32 and a recuperator 33 which are secured at one end to the cylinder 6 and at the other end to the pressure plate 13. This arrangement provides a similar braking effect to that provided by the arrangement of FIGS. 1-4.

The operation of the impulse transmitter is as follows: The impulse transmitter is set up such that the muzzle of the barrel R of the piece at elevation of the barrel is placed exactly over the centering cone 15 and thus abuts fully against the pressure plate 16. The recuperator thus presses the impulse transmitter against the muzzle of the barrel R with a force which is less than the recuperator force of the piece in the resting position. Elevations of the barrel which are greater or less than 0 can be taken into account by tilting the impulse transmitter together with the rails.

The cartridge 9 is detonated either electrically or mechanically by means of the ignition device. Due to the pressure of the gases from the propellent charge the piston moves rapidly forward against the action of the recuperator spring 25 and with the pressure plate 16 pushes the abutting barrel R of the piece in the recoil direction until the resultant of all the forces on the impulse transmitter side acting on the piston and the pressure plates 13 and 16 imparts a braking retardation to the piston 10, which is greater than the braking retardation of the parts of the piece to be tested which are now recoiling freely. This condition is achieved as soon as the piston 10 has uncovered the outlet apertures 11 permitting the powder gases to escape into the chamber 12 and then into the atmosphere with a hissing sound through the venting valve arrangement 26.

The piston 10 with the pressure plates 13, 16 is retarded at the end of the working stroke by the hydraulic braking device due to the recoil speed of the impulse transmitter. In the course of the piston stroke, the displacement body 21 passes the housing shoulder 19a and the subsequent taper 19b and the sudden taper of the cross section of aperture causes the braking action to occur. The same effect is also achieved with the hydraulic brakes 32.

The kinetic energy produced during braking is transformed into heat in the braking device causing the brake fluid to expand. Furthermore, additional space for the brake fluid is required in that the rear end of the piston 10 entering the brake housing 19 has a smaller cross section than the part of the piston leaving at the front end.

The surplus volume of brake fluid collected in the brake housing due to the thermal expansion and outward flow from the compensating chamber 23 must filled with brake fluid when there are temperature variations or when there is a leakage of fluid and to avoid the possibility of high static excess pressure. This is achieved in that opposite the fluid-filled compensating chamber 23 is the compensating piston 22, which is acted upon by a gas under pressure which fills the chamber 24. Thus, the compensating piston 22 is biased toward the chamber 23 such that the brake fluid is maintained under pressure in the stationary position of the impulse transmitter within the compensating chamber 23 and within the brake cylinder 19.

The recuperator spring 25 or the recuperator 33 (FIG. 5) serves for returning the piston 10 to its initial position. Also the entire arrangement which travels on the track 3 of rails is returned to its initial position by the recoil brake 4 and the recuperator 5.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It should therefore be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. An impulse transmitter for dynamic devices for testing pieces of ordnance comprising a housing, chamber means within said housing, cylinder means arranged within said housing and having apertures for communicating with said chamber means, a piston movably mounted within said cylinder means to have a working stroke and having one end portion projecting outwardly from said housing for abutment against the muzzle of a barrel of the piece of ordnance to be tested, said piston closing said apertures in said cylinder means in the initial rest position thereof, a propellent charge disposed within said cylinder means and adapted to be ignited to form gases for moving said piston forwardly against the barrel of the piece of ordnance to simulate the recoil action of the barrel after firing of the piece of ordnance, the movement of said piston uncovering said apertures'in said cylinder means to permit the charge gases to flow therethrough into said chamber means, said chamber means having a volume larger than the volume of the portion of said cylinder means through which said piston moves during the stroke thereof, and venting valve means being provided in said housing for communicating between said chamber means and the atmosphere to permit the outwardly flow of gases from said chamber means to the atmosphere.

2. An impulse transmitter as defined in claim 1 including a hydraulic braking means associated with said piston which acts against said impulse transmitter housing and said cylinder means, said braking means comprising a brake housing concentrically surrounding said piston and having an inner surface which tapers in the forward direction of the piston stroke, a displacement body cooperating with the inner surface of said housing and located on the outer portion of said piston, said brake housing being filled with brake fluid.

3. An impulse transmitter as defined in claim 2 wherein said piston is provided with a bore having a compensating piston movably arranged therein, said compensating piston defining a compensating chamber and a pressure chamber within said bore, said piston having an aperture therethrough for communication between said compensating chamber and said brake housing.

4. An impulse transmitter as defined in claim 1 including a brake means having at least one buffer brake positioned in said housing proximate to said piston and parallel to the axis thereof.

5. An impulse transmitter as defined in claim 1 wherein said piston is provided with a recuperator spring abutting against said cylinder means and said piston for biasing said piston into the initial rest position thereof.

6. An impulse transmitter as defined in claim 1 including first and second pressure plates having an elastic intermediate plate therebetween provided on the end of said piston which projects from said impulse transmitter housing by a srping biased tie-rod for secur ing said plates in the axial direction and clamping means for securing the plates and the pistonrin-the radial direction for centering the plates and the piston with respect to the barrel of the piece of ordnance.

7. An impulse transmitter as defined in claim 6 wherein said first pressure plate is adapted to abut against the barrel of the piece of ordnance and includes an axial projection for extending into the barrel and said second pressure plate abuts against said piston.

8. An impulse transmitter as defined in claim 1 wherein said outlet apertures of said cylinder means are provided with deflecting means positioned in said chamber means for protecting the wall of said chamber means from the hot gases flowing therethrough.

9. An impulse transmitter as defined in claim 1 wherein said cylinder means includes a powder chamber for receiving said propellent charge, at least one sleeve adapted for insertion in said chamber to vary the size of said chamber to permit propellent charges in the forms of cartridges of different calibers to be used in said powder chamber.

10. An impulse transmitter as defined in claim ,9 wherein said sleeve abuts against the powder chamber and sealing means are provided for sealing said sleeve within said chamber.

11. An impulse transmitter as defined in claim 10 including a plurality of sleeves coaxially arranged within said chamber, each of said sleeves having a different thickness.

12. An impulse transmitter as defined in claim 1 wherein the volume of said chamber means is at least ten times greater than the volume of the cylinder means through which the piston moves.

13. An impulse transmitter as defined in claim 12 including a hydraulic braking means associated with said piston which acts against said impulse transmitter housing and said cylinder means, said braking means comprising a brake housing concentrically surrounding said iston and having an inner surface which tapers in the orward direction of the piston stroke, a displacement body cooperating with the innersurface of said housing and located on the outer portion of said piston, said brake housing being filled with brake fluid.

14. An impulse transmitter as defined in claim 13 wherein said piston is provided with a bore having a compensating piston movably arranged therein, said compensating piston defining a compensating chamber and a pressure chamber within said bore, said piston having an aperture therethrough for communication between said compensating chamber and said brake housing.

15. An impulse transmitter as defined in claim 14 wherein saidpiston is provided with a recuperator spring abutting against said cylinder means and said piston for biasing said piston into the initial rest position thereof.

16. An impulse transmitter as defined in claim 15 including first and second pressure plates having an elastic intermediate plate therebetween provided on the end of said piston which projects from said impulse transmitter housing by a spring biased tie-rod for securing said plates in the axial direction and clamping means for securing the plates and the piston in the radial direction for centering the plates and the piston with respect to the barrel of the piece of ordnance.

17. An impulse transmitter as defined in claim 15 wherein said first pressure plate is adapted to abut against the barrel of the piece of ordnance and includes an axial projection for extending into the barrel and said second pressure plate abuts against said piston.

18. An impulse transmitter as defined in claim 17 wherein said outlet apertures of said cylinder means are provided with deflecting means positioned in said chamber means for protecting the wall of said chamber means from the hot gases flowing therethrough.

19. An impulse transmitter as defined in claim 18 wherein said cylinder means includes a powder chamber for receiving said propellent charge, at least one sleeve adapted for insertion in said chamber to vary the size of said chamber to permit propellent charges in the forms of cartridges of different calibers to be used in said powder chamber.

20. An impulse transmitter as defined in claim 19 wherein said sleeve abuts against the powder chamber and sealing means are provided for sealing said sleeve within said chamber.

21. An impulse transmitter as defined in claim 19 wherein said venting valve means is a labyrinth throttle valve.

22. An impulse transmitter as defined in claim 1 further comprising wheels mounted on said housing for movement along a pair of rails affixed to a support 

1. An impulse transmitter for dynamic devices for testing pieces of ordnance comprising a housing, chamber means within said housing, cylinder means arranged within said housing and having apertures for communicating with said chamber means, a piston movably mounted within said cylinder means to have a working stroke and having one end portion projecting outwardly from said housing for abutment against the muzzle of a barrel of the piece of ordnance to be tested, said piston closing said apertures in said cylinder means in the initial rest position thereof, a propellent charge disposed within said cylinder means and adapted to be ignited to form gases for moving said piston forwardly against the barrel of the piece of ordnance to simulate the recoil action of the barrel after firing of the piece of ordnance, the movement of said piston uncovering said apertures in said cylinder means to permit the charge gases to flow therethrough into said chamber means, said chamber means having a volume larger than the volume of the portion of said cylinder means through which said piston moves during the stroke thereof, and venting valve means being provided in said housing for communicating between said chamber means and the atmosphere to permit the outwardly flow of gases from said chamber means to the atmosphere.
 2. An impulse transmitter as defined in claim 1 including a hydraulic braking means associated with said piston which acts against said impulse transmitter housing and said cylinder means, said braking means comprising a brake housing concentrically surrounding said piston and having an inner surface which tapers in the forward direction of the piston stroke, a displacement body cooperating with the inner surface of said housing and located on the outer portion of said piston, said brake housing being filled with brake fluid.
 3. An impulse transmitter as defined in claim 2 wherein said piston is provided with a bore having a compensating piston movably arranged therein, said compensating piston defining a compensating chamber and a pressure chamber within said bore, said piston having an aperture therethrough for communication between said compensating chamber and said brake housing.
 4. An impulse transmitter as defined in claim 1 including a brake means having at least one buffer brake positioned in said housing proximate to said piston and parallel to the axis thereof.
 5. An impulse transmitter as defined in claim 1 wherein said piston is provided with a recuperator spring abutting against said cylinder means and said piston for biasing said piston into the initial rest position thereof.
 6. An impulse transmitter as defined in claim 1 including first and second pressure plates having an elastic intermediate plate therebetween provided on the end of said piston which projects from said impulse transmitter housing by a srping biased tie-rod for securing said plates in the axial direction and clamping means for securing the plates and the piston in the radial direction for centering the plates and the piston with respect to the barrel of the piece of ordnance.
 7. An impulse transmitter as defined in claim 6 wherein said first pressure plate is adapted to abut against the barrel of the piece of ordnance and includes an axial projection for extending into the barrel and said second pressure plate abuts against said piston.
 8. An impulse transmitter as defined in claim 1 wherein said outlet apertures of said cylinder means are provided with deflecting means positioned in said chamber means for protecting the wall of said chamber means from the hot gases flowing therethrough.
 9. An impulse transmitter as defined in claim 1 wherein said cylinder means includes a powder chamber for receiving said propellent charge, at least one sleeve adapted for insertion in said chamber to vary the size of said chamber to permit propellent charges in the forms of cartridges of differenT calibers to be used in said powder chamber.
 10. An impulse transmitter as defined in claim 9 wherein said sleeve abuts against the powder chamber and sealing means are provided for sealing said sleeve within said chamber.
 11. An impulse transmitter as defined in claim 10 including a plurality of sleeves coaxially arranged within said chamber, each of said sleeves having a different thickness.
 12. An impulse transmitter as defined in claim 1 wherein the volume of said chamber means is at least ten times greater than the volume of the cylinder means through which the piston moves.
 13. An impulse transmitter as defined in claim 12 including a hydraulic braking means associated with said piston which acts against said impulse transmitter housing and said cylinder means, said braking means comprising a brake housing concentrically surrounding said piston and having an inner surface which tapers in the forward direction of the piston stroke, a displacement body cooperating with the inner surface of said housing and located on the outer portion of said piston, said brake housing being filled with brake fluid.
 14. An impulse transmitter as defined in claim 13 wherein said piston is provided with a bore having a compensating piston movably arranged therein, said compensating piston defining a compensating chamber and a pressure chamber within said bore, said piston having an aperture therethrough for communication between said compensating chamber and said brake housing.
 15. An impulse transmitter as defined in claim 14 wherein said piston is provided with a recuperator spring abutting against said cylinder means and said piston for biasing said piston into the initial rest position thereof.
 16. An impulse transmitter as defined in claim 15 including first and second pressure plates having an elastic intermediate plate therebetween provided on the end of said piston which projects from said impulse transmitter housing by a spring biased tie-rod for securing said plates in the axial direction and clamping means for securing the plates and the piston in the radial direction for centering the plates and the piston with respect to the barrel of the piece of ordnance.
 17. An impulse transmitter as defined in claim 15 wherein said first pressure plate is adapted to abut against the barrel of the piece of ordnance and includes an axial projection for extending into the barrel and said second pressure plate abuts against said piston.
 18. An impulse transmitter as defined in claim 17 wherein said outlet apertures of said cylinder means are provided with deflecting means positioned in said chamber means for protecting the wall of said chamber means from the hot gases flowing therethrough.
 19. An impulse transmitter as defined in claim 18 wherein said cylinder means includes a powder chamber for receiving said propellent charge, at least one sleeve adapted for insertion in said chamber to vary the size of said chamber to permit propellent charges in the forms of cartridges of different calibers to be used in said powder chamber.
 20. An impulse transmitter as defined in claim 19 wherein said sleeve abuts against the powder chamber and sealing means are provided for sealing said sleeve within said chamber.
 21. An impulse transmitter as defined in claim 19 wherein said venting valve means is a labyrinth throttle valve.
 22. An impulse transmitter as defined in claim 1 further comprising wheels mounted on said housing for movement along a pair of rails affixed to a support base, and a recuperator and a recoil brake arranged in parallel between the rails and secured between said housing and the support base. 